scholarly journals The role of dislocation-solute interactions on the creep behaviour of binary Mg–RE alloys

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jing Li ◽  
Jialin Wu ◽  
Li Jin ◽  
Mert Celikin ◽  
Fenghua Wang ◽  
...  

AbstractThe effect of dislocation-RE atoms interactions on the creep behaviour has been studied via creep testing and HAADF-STEM analysis of two extruded alloys; Mg–0.5Ce and Mg–2Gd (wt%). Almost no Ce atoms are detected in the Mg matrix due to the low solid solubility and faster diffusion rate in as-extruded condition. However, Gd solute segregations are observed along dislocations and hexagonal dislocation patterns. Such segregations can not only pin the dislocation motion and enhance the creep strengthening via dislocation patterns, but also lead to dynamic precipitation. Thus, combing with the stress exponent values, the transition of creep mechanism between Mg–0.5Ce alloys and Mg–2Gd alloys has been found and dislocation-Gd atoms interactions are determined to be the main factor for superior creep resistance of Mg–2Gd alloys.

2020 ◽  
Author(s):  
Jing Li ◽  
Jialin Wu ◽  
Li Jin ◽  
Mert Celikin ◽  
Fenghua Wang ◽  
...  

Abstract The effect of dislocation-RE atoms interactions on the creep behaviour has been studied via creep testing and HAADF-STEM analysis of two extruded alloys; Mg-0.5Ce and Mg-2Gd (wt.%). Almost no Ce atoms are detected in the Mg matrix due to the low solid solubility in as-extruded condition. However, Gd solute segregations are observed along dislocations and hexagonal dislocation patterns. Such segregations can not only pin the dislocation motion and enhance the creep strengthening via dislocation patterns, but also lead to dynamic precipitation. Thus, combing with the stress exponent values, the transition of creep mechanism between Mg-0.5Ce alloys and Mg-2Gd alloys has been found and dislocation-Gd atoms interactions are determined to be the main factor for superior creep resistance of Mg-2Gd alloys.


Acta Naturae ◽  
2016 ◽  
Vol 8 (2) ◽  
pp. 79-86 ◽  
Author(s):  
P. V. Elizar’ev ◽  
D. V. Lomaev ◽  
D. A. Chetverina ◽  
P. G. Georgiev ◽  
M. M. Erokhin

Maintenance of the individual patterns of gene expression in different cell types is required for the differentiation and development of multicellular organisms. Expression of many genes is controlled by Polycomb (PcG) and Trithorax (TrxG) group proteins that act through association with chromatin. PcG/TrxG are assembled on the DNA sequences termed PREs (Polycomb Response Elements), the activity of which can be modulated and switched from repression to activation. In this study, we analyzed the influence of transcriptional read-through on PRE activity switch mediated by the yeast activator GAL4. We show that a transcription terminator inserted between the promoter and PRE doesnt prevent switching of PRE activity from repression to activation. We demonstrate that, independently of PRE orientation, high levels of transcription fail to dislodge PcG/TrxG proteins from PRE in the absence of a terminator. Thus, transcription is not the main factor required for PRE activity switch.


Transient creep following stress reductions has been analysed by the method described by McLean (1980) to determine the friction stress σ 0 as a function of temperature and directional solidification conditions for the γ-γ'-Cr 3 Cr 2 in-situ composite and for the γ-γ' matrix alloy. These values of σ 0 are identical to the flow stresses at creep strain rates and can be identified with the sums of the barriers to dislocation motion through the matrix by climb around γ'-particles and Orowan bowing between the carbide fibres. The friction stress and the kinetics of deformation of the composite are determined by the matrix behaviour, whereas its creep strength depends on the distribution of stress between fibre and matrix. When the steady-state creep behaviour of γ-γ'-Cr 3 C 2 is analysed by using the usual power law description in terms of the effective stress σ — σ 0 , rather than the applied stress σ, the stress exponent is ca 4 and the activation energy is similar to the activation energy of self-diffusion for nickel. The results provide strong evidence for the operation of recovery-creep in both the composite and matrix alloys.


2021 ◽  
Vol 83 (10) ◽  
Author(s):  
Alfonso Ruiz-Herrera ◽  
Pedro J. Torres

AbstractIn this paper, we analyze the influence of the usual movement variables on the spread of an epidemic. Specifically, given two spatial topologies, we can deduce which topology produces less infected individuals. In particular, we determine the topology that minimizes the overall number of infected individuals. It is worth noting that we do not assume any of the common simplifying assumptions in network theory such as all the links have the same diffusion rate or the movement of the individuals is symmetric. Our main conclusion is that the degree of mobility of the population plays a critical role in the spread of a disease. Finally, we derive theoretical insights to management of epidemics.


1935 ◽  
Vol 31 (8-9) ◽  
pp. 1114-1114

The role of calcium, platelets, and other factors that were associated with bleeding was not confirmed in jaundice. Carr and Toote found that the amino acid cysteine was the main factor impeding blood clotting. In obstructive jaundice, this amino acid accumulates in the blood and in in vitro experiments and, when administered to animals, causes a deterioration in blood clotting.


Author(s):  
G. A. Larionov ◽  
◽  
O. Yu. Сhecheneshkina ◽  
E. S. Yatrusheva ◽  
N. I. Yendierov ◽  
...  

The main factor of determining the level of sanitary and hygienic indicators of the quality of milk produced is the hygiene of milking cows. The study of the role of hygiene of milking is of great importance for a correct understanding of the ways of solving the problem of obtaining high quality milk. Special attention of scientists and practitioners in recent years are focused on the development and implementation of highly effective detergents and disinfectants in the production of milk of cows. Many researchers and practitioners have directed their work to developing measures to prevent the entry of pathogenic microflora into milk during and after milking cows. In spite of many researches carried out, aimed at controlling the number of somatic cells in milk with the use of different products based on lactic acid, chlorhexidine and iodine, the problem of high quality milk production remains unresolved. In our work results of researches on the use of probiotic means for treatment of udders of cows are given. Processing the udder of cows with probiotic means before milking by Skin Cleaner, after milking by PIP Cow Teat Cleaner reduced the amount of somatic cells in cow milk 12,8-84,0%. The use of probiotic means Biomastim lowed somatic cell count of 18,4-51,9%. Microbiological contamination of milk using probiotic means for processing the udder before milking Skin Cleaner, after milking PIP Cow Teat Cleaner decreased 4,9- 70,4 times. The application of probiotic means Biomastim after milking on the teats led to the decrease in milk of cows QMAFAnM 5,0-6,6 times.


Author(s):  
Xiao-Hui Chen ◽  
Lei Liu ◽  
Jinbo Li ◽  
Fayun Zhang

Abstract Al7075–Ti–Y natural composites were prepared by using a combination of ultrasonic vibration and casting. The effects of titanium (Ti) and yttrium (Y) on the nucleation of primary α-Al were studied and the influencing mechanism of Y on the TiAl3 formation was analysed. Furthermore, a reaction kinetics model of TiAl3 under ultrasonic vibration was established. The results showed that the uniformly distributed TiAl3 and Al3Y nano-particles resulted in grain refinement. Y changed the morphology of TiAl3 and the appearance of corrosion pits was related to the fact that Y was dissolved within the TiAl3 structure to form Ti(Al,Y)3. The established model revealed that ultrasonic vibration significantly promoted the formation of TiAl3, and that ultrasonic time was the main factor affecting its growth.


2021 ◽  
Vol 8 ◽  
pp. 199-203
Author(s):  
Tamara A. Samoyluk ◽  
Anastasia S. Popova ◽  
Aelita V. Shaburova

In a market economy, the competitiveness of an enterprise is ensured by the introduction of innovations. In order to remain innovative, enterprises need high-quality human resources. Investments in human resources, as the main factor of innovative growth, determine the ability of employees to transform their existing knowledge, skills and abilities into high-tech products, highly qualified services.


2019 ◽  
Vol 7 ◽  
Author(s):  
Jana Kovaľová ◽  
Zuzana Birknerová ◽  
Miroslav Frankovský ◽  
Eva Benková

The role of sellers is changing in a turbulent business environment and only the sellers who provide first class services and approach to them in a responsible way can survive among competitors. Customers perceive it as an added value and have a good feeling from buying. It is just sellers who are becoming the main factor that contributes to the competitiveness of a whole organization. The segmentation of customers into individual generations enables us to better understand their preferences and requirements, it is then possible to predict their tendencies in buying behaviour and thus increasing the success of sales. The main aim of the paper is to present the issue of different assessment of sellers’ behaviour by the customers of the Baby Boomers, Generation X, Generation Y and Generation Z. In connection with these differences, the aim of the research is to identify generational differences in the assessment of manipulative, assertive, stressed and engaged behaviour of sellers, as well as to analyse the determinants that affect the buying behaviour of customers. The research was conducted using a questionnaire method and mathematical-statistical methods on a sample of 207 respondents. The research results confirm the existence of statistically significant differences in assessing the determinants of sellers’ behaviour from the perspective of individual customer generations.


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